<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    
</body>
<script>
    let year = prompt('请输入年份')
    if((year % 4 === 0 && year % 100 !== 0)|| year % 400 === 0)
{
    alert(year + '年是闰年')
}
else
{
    alert(year + '年是平年')
}
</script>
</html>